Reference is made to PCT Application WO 2004/056172 filed Dec. 23, 2002 and relating to an irrigation mat for irrigating potted plants. Water is supplied to the irrigation mat by overhead sprinklers and the mats absorb and retain water and feed the potted plants through holes formed at the bottom of the pots. The present invention is an improvement of this type of irrigation mat.
There is further described in U.S. Pat. No. 5,839,659 a capillary root zone irrigation system utilizing an irrigation mat. The irrigation mat is also provided with a capillary cloth sandwiched between a polyethylene base sheet and a top weed mat. Water is supplied to the capillary cloth by polyethylene rigid pipes which have perforations therein. A disadvantage of such an irrigation mat is that the mat must be assembled on site with rigid water supply pipes. Accordingly, the mat may be rolled up for shipping and storage but it is up to the user to purchase perforated pipes and assemble them in pockets which are stitched along the top layer of the mat. Accordingly, the mat cannot be rolled with the pipes and must be sold separately. The construction of the mat is also expensive as one needs to stitch channels at spaced apart intervals within the mat. Often there are too many channels and too much water supplied to the mat. For long spans of mats, it is also necessary to form joints between PVC pipes to weld them together whereby to span the entire mat. This is a time-consuming job. Also, these pipes cause the mat to bulge on the top surface thereof making that part of the mat non-usable for laying pots thereover. Accordingly, it is not practical for use in nurseries.
Finally, installation of very long capillary mats in the field or on greenhouses benches is not recommended, as plant root diseases may spread over large surfaces. Also, water may drain from upward to downward position, increasing the risk of non-uniform water distribution between pots. Therefore, it is preferable to have smaller pieces of mat neighboring each other for a better uniformity of water distribution between pots. However, placing smaller pieces of mat together in a uniform assemblage is time and resources consuming and not practical in nurseries and greenhouses.